Is 5 minutes enough time to change trains from the IC (from The Hague to Rotterdam) to Thalys (rotterdam to Paris)? That is what the web sites are showing when I go to buy tickets.
Why play it so close? Take a train from Den Haag 15 or 30 mins earlier.
Dutch trains, such as the Intercity from Den Haag (The Hague) to Rotterdam, don't come with a reservation. Your ticket to Paris will be good for any train from Den Haag to Rotterdam. These trains run every 15 mins (like most trains in this part of the country).
It is enough, the station has a central underground passageway with escalators to and from all platforms. I do suggest also that you take an earlier train from Den Haag (your Thalys ticket is valid on any Dutch domestic train connecting to your Thalys, even if it only indicates one specific train).
If you ae traveling first class, you can make free use of the NS International Lounge next to platform 1.